A deuteron tensor polarimeter with the highest available figure-of-merit was developed in order to measure the tensor polarization t20 in electron and pion elastic scattering from the deuteron. The polarimeter was calibrated at the Berkeley 88 cyclotron with the associated polarized ion source. The feasibility of the method was demonstrated by measuring t20 in pion-deuteron elastic scattering at LAMPF. The application of this method to e-d elastic scattering will be discussed for the momentum transfer range 2 fm−2 < q2 < 30 fm−2.